Organic EL device has many advantages such as self-emitting, wider viewing angles, faster response speeds and highly luminescence. Their simpler fabrication and capable of giving clear display comparable with LCD, making organic EL device an industry display of choice. Organic EL device contain emissive materials which are arranged between a cathode and a anode, when a applied driving voltage is added, an electron and a hole were injected into the emissive layer and recombined to form an exciton. The exciton which results from an electron and a hole recombination have a singlet spin state or triplet spin state. Luminescence from a singlet spin state emits fluorescence and luminescence from triplet spin state emits phosphorescence.
Organic EL device are generally composed of functionally divided organic multi-layers, e.g., hole injection layer (HIL), hole transporting layer (HTL), emissive layer (EML), electron transporting layer (ETL) and electron injection layer (EIL) and so on. A emissive material have good charge carrier mobility and excellent operational durability can lower driving voltage and power consumption, Increasing efficiency and half-lifetime of Organic EL device.
For full-colored flat panel displays in AMOLED, the compounds used for the blue emissive layer are still unsatisfactory in half-lifetime and emissive colour. Many fluorene compounds are used for fluorescence blue host in emissive layer. U.S. Pat. No. 7,691,492 used 1,1′-(9,9-dimethyl-9H-fluorine-2,7-diyl)dipyrene (DFDP) as host for blue emissive electroluminescence device. U.S. Pat. No. 8,158,835 described fluorene compound used as blue, green, or red host. U.S. Pat. No. 8,110,294 also claim fluorene compound used as phosphorescence host. These compounds still have disadvantages for industrial practice use. Especially for AMOLED, except prolong half-lifetime, deep blue emission (CIE y coordinates under 0.15) is necessary for improvement.